Parrish Randall R, Thirlwall Matthew F, Pickford Chris, Horstwood Matthew, Gerdes Axel, Anderson James, Coggon David
Department of Geology, University of Leicester and NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Notts, NG12 5GG, UK.
Health Phys. 2006 Feb;90(2):127-38. doi: 10.1097/01.hp.0000174809.43871.54.
Accidental exposure to depleted or enriched uranium may occur in a variety of circumstances. There is a need to quantify such exposure, with the possibility that the testing may post-date exposure by months or years. Therefore, it is important to develop a very sensitive test to measure precisely the isotopic composition of uranium in urine at low levels of concentration. The results of an interlaboratory comparison using sector field (SF)-inductively coupled plasma-mass spectrometry (ICP-MS) and multiple collector (MC)-ICP-MS for the measurement of uranium concentration and U/U and U/U isotopic ratios of human urine samples are presented. Three urine samples were verified to contain uranium at 1-5 ng L and shown to have natural uranium isotopic composition. Portions of these urine batches were doped with depleted uranium (DU) containing small quantities of U, and the solutions were split into 100 mL and 400 mL aliquots that were subsequently measured blind by three laboratories. All methods investigated were able to measure accurately U/U with precisions of approximately 0.5% to approximately 4%, but only selected MC-ICP-MS methods were capable of consistently analyzing U/U to reasonable precision at the approximately 20 fg L level of U abundance. Isotope dilution using a U tracer demonstrates the ability to measure concentrations to better than +/-4% with the MC-ICP-MS method, though sample heterogeneity in urine samples was shown to be problematic in some cases. MC-ICP-MS outperformed SF-ICP-MS methods, as was expected. The MC-ICP-MS methodology described is capable of measuring to approximately 1% precision the U/U of any sample of human urine over the entire range of uranium abundance down to <1 ng L, and detecting very small amounts of DU contained therein.
在各种情况下都可能发生意外接触贫化铀或浓缩铀的情况。有必要对这种接触进行量化，而检测可能在接触发生数月或数年之后进行。因此，开发一种非常灵敏的测试方法以精确测量低浓度尿液中铀的同位素组成非常重要。本文介绍了使用扇形磁场（SF）-电感耦合等离子体质谱法（ICP-MS）和多接收器（MC）-ICP-MS对人类尿液样本中铀浓度以及U/U和U/U同位素比率进行测量的实验室间比对结果。已验证三个尿液样本中铀含量为1-5纳克/升，且具有天然铀同位素组成。这些尿液批次的部分样本用含有少量U的贫化铀（DU）进行掺杂，然后将溶液分成100毫升和400毫升的等分试样，随后由三个实验室进行盲测。所研究的所有方法都能够准确测量U/U，精度约为0.5%至约4%，但只有选定的MC-ICP-MS方法能够在U丰度约为20飞克/升的水平上始终如一地以合理精度分析U/U。使用U示踪剂的同位素稀释法表明，采用MC-ICP-MS方法测量浓度的精度优于±4%，不过在某些情况下，尿液样本中的样品异质性被证明是个问题。正如预期的那样，MC-ICP-MS的性能优于SF-ICP-MS方法。所描述的MC-ICP-MS方法能够在低至<1纳克/升的整个铀丰度范围内，以约1%的精度测量任何人类尿液样本的U/U，并检测其中所含的极少量DU。
